In the electronic arts, encapsulation of electromechanical or hybrid semiconductor arrangements or the like is required in order to stabilize many of the ambient conditions to which these elements are subjected and to protect them from extremes of other conditions. This encapsulation or packaging has been variously accomplished. In particular, where hermetic sealing is required, metallic enclosures with glass-to-metal electrical lead feed through has been the standard approach.
When the package is small and appreciable voltage and power levels are extant, the conventional glass-to-metal electrical feed through arrangements are difficult to manufacture and relatively expensive. Moreover, such seals are subject to breakage and consequent failure due to incidental mechanical stresses.
Prior art packages of the type and size contemplated in the invention have been made from such materials as Kovar, steel, aluminum, copper, molybdenum and ceramic materials, all of which are relatively heavy and costly.
The known pertinent prior art is typically described in the patent literature, as follows:
U.S. Pat. No. 3,621,112 proposes a ferrous metal enclosure with the aforementioned glass-to-metal seals for the electrical feed through leads.
U.S. Pat. No. 3,575,546 shows a plastic body with "snap-in" header which is not hermetically sealable and does not provide a heat sink feature.
U.S. Pat. No. 3,548,076 is further typical of a metallic enclosure for a solid-state hybrid. Glass-to-metal seals are shown to provide the relatively large number of electrical leads required for connections to the hybrid sealed therein.
U.S. Pat. No. 3,538,597 deals with a cover plate for a "flat pack" containing microcircuits or the like. The Kovar cover plate (lid) is soldered onto an apparently metallic housing (although the insulation of electrical leads passing therethrough is not shown).
U.S. Pat. No. 2,932,684 appears to be a nonrepairable encapsulation device of typical early form. Many individual parts are included in a relatively massive, single power transistor package.
U.S. Pat. No. 3,419,763 contemplates the paralleling of a plurality of individual solid-state devices within a sealed housing structure with heat sinking features. The familiar glass-to-metal electrical lead seals through its base and metallized ceramic seals for top cover penetration are required in this package and overall weight is obviously relatively large.
U.S. Pat. No. 3,433,885 is another "all metal" enclosure for a single power semiconductor device. This enclosure is not adapted for multiple lead circuits such as semiconductor hybrids and is relatively heavy.
Devices of the prior art including those specifically mentioned hereabove suffer from the disadvantages of high cost of manufacture, relatively large weight factors and poor adaptability where multiple electrical connections are required. Wherever glass-to-metal or ceramic-to-metal seals are used, there is a hazard of chipping, fracture, loss of hermetic seal and electrical breakdown. Unintended mechanical stress applied to the leads passing through such seals significantly increases the hazard of such damage and consequent electrical breakdown.
The manner in which the invention deals with the disadvantages inherent in the prior art to produce a novel structure having particular advantages will be understood as this description proceeds.